From Lightweight Ceramic Heat Sinks To Interface Solutions For Heat Dissipation

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While going through electronics product reviews, you might have come across phrases like, “The phone heats up on intensive gaming” or “The device feels warm after constant use.” According to Ramanan, vice president – engineering, defence solutions, Mistral Solutions, “Due to this inefficiency of electronic devices, a vast portion of electrical energy is converted to heat, calling for a heat sink and other solutions being put in place.”

Electronic devices exhibit high heat dissipation levels over a very small surface area. The heat thus dissipated by electronic devices in a product, if not managed or removed, may lead to the malfunction of the device, deteriorate the product performance, and may also be hazardous to the environment and users of such products. It is therefore essential to implement efficient thermal management techniques at the product level. Thermal management designs for the envelope the product has to function within can be arrived at by carrying simulations and analysis which yields the exact information of the thermal behavior of devices and the product as a whole. The findings from such analysis is applied to arrive at the appropriate and optimal design of the product.

Thermal solutions come in handy while thinking of a way to solve this problem. Heat dissipation needs of today’s components are more challenging than ever. System airflow and its impact on heat sink design is a very important factor in applications generating sufficient heat. “Telecom, automobiles and lighting are some applications that require major use of thermal solutions,” says Dr Misra, director – research and development, Henkel Adhesive Technologies.

thermal paste as heat sink
Fig. 1: Applying thermal paste on the processor

Consider an efficient heat sink

Ongoing increase in power usage among devices such as processors and insulated-gate bipolar transistors results in higher capacity cooling requirements to remove excess heat. To cool hotter components, you may use large fans, heat sink and increase surface area. Using higher-performance interface material between the case and the heat sink also improves cooling performance

Heat transfer occurs when two surfaces have different temperatures, thus causing heat energy to transfer from the hotter surface to the colder one. Some tips from industry experts in the box titled ‘Application tips for heat sink design,’ should be helpful in designing one.

The latest in heat removal

“A clear understanding of the amount of heat generated and the rate of generation are essential to arrive at the size and design of the heat sink,” says Ramanan. “The choice of thermally conductive pads as a shunt between heat sink and the devices is also determined by these two factors,” he adds. On a more general note, radial and grid patterns (pin fin) are being used by designers today for better heat dissipation. Radial fins provide ease in design, while grid patterns allow for a much higher surface area to aid heat loss.

As for the material, aluminium alloys have been the material of choice for the past decade for efficient cooling. Aluminium also remains popular for its conductivity, light weight and low cost, relative to other metals such as copper. To create more complex designs, manufacturers have also employed high-quality alloys like forged aluminium.

Ceramics, thermally-conductive plastics and graphite are also being experimented with. Inorganic ceramics, non-metallic and non-corrosive materials are already being used in LEDs. Heat conduction and electric insulation make these ideal for heat sink applications.

Thermally-conductive plastics, or thermoplastics that are loaded with a conductive material, such as aluminium nitride are naturally non-corrosive, making these ideal for outdoor applications. Thermoplastics are also 20 to 30 per cent less expensive than aluminium as these are simpler to make.

Italian luminaire manufacturer, Reggiani Lighting, combines copper and extruded aluminium to reap the best of both metals in LEDs. These materials are undergoing a lot of experiments. Made from graphite, hitherm is a lightweight flexible material. Carbon being an excellent conductor of heat, it enables this material to be a very good heat sink. However, price point of these solutions is relatively high.

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